Copy-number mutants of the plasmid carrying the replication origin of the Escherichia coli chromosome: evidence for a control region of replication.

A composite plasmid (pXX11) was constructed by joining of an oriC plasmid (pMCR115) carrying the replication origin (oriC) of the Escherichia coli chromosome and a mini-F plasmid (pSC138) carrying the ampicillin-resistance gene (bla). Plasmid pXX11 can replicate, by using oriC, in Hfr cells and mafA mutant cells that cannot support replication of an F plasmid. This plasmid is stably maintained in these host cells during cell growth even under nonselective conditions by use of the partition mechanism of the mini-F genome. In contrast to other oriC plasmids reported previously, pXX11 has no detectable effect on host cell growth. Higher copy-number (Cop-) mutants of pXX11 were isolated, and some of them were found to carry an insertion or deletion within a region derived from the E. coli chromosome. This region, designated cop (copy number), covers about 0.7 kilobase pair and is located approximately 3 kilobase pairs away from the oriC region at the side opposite the asn gene. Evidence suggests that the normal cop region locted on the oriC plasmid acts to reduce the copy number of the plasmid. Plasmid pXX11 complements the uncB402 mutation located on the host chromosome, but some of the Cop- plasmids do not, suggesting that the cop region is vey closely linked to uncB.     

Two patients treated with pegylated interferon/ribavirin/telaprevir triple therapy for recurrent hepatitis C after living donor liver transplantation

It is difficult to use protease inhibitors in patients with recurrent hepatitis C virus (HCV) infection after liver transplantation (LT) due to interaction with immunosuppressive drugs. We report our experience with two patients treated with telaprevir (TVR) combined with pegylated interferon/ribavirin (PEG IFN/RBV) for recurrent HCV genotype 1 infection after LT. The first was a 63‐year‐old man with HCV‐related liver cirrhosis, who failed to respond to IFN‐β plus RBV after LT. Treatment was switched to PEG IFN‐α‐2b plus RBV and TVR was started. The donor had TT genotype of interleukin (IL)‐28 single nucleotide polymorphisms (SNP) (rs8099917). The recipient had TT genotype of IL‐28 SNP (rs8099917). Completion of 12‐week triple therapy was followed by PEG IFN‐α‐2b plus RBV for 36 weeks. Finally, he had sustained viral response. The second was a 70‐year‐old woman with HCV‐related liver cirrhosis and hepatocellular carcinoma. She failed to respond to PEG IFN‐α‐2b plus RBV after LT, and was subsequently switched to PEG IFN‐α‐2b/RBV/TVR. Genotype analysis showed TG genotype of IL‐28 SNP for the donor, and TT genotype of IL‐28 SNP for the recipient. Serum HCV RNA titer decreased below the detection limit at 5 weeks. However, triple therapy was withdrawn at 11 weeks due to general fatigue, which resulted in HCV RNA rebound 4 weeks later. Both patients were treated with cyclosporin, starting with a small dose to avoid interactions with TVR. TVR is a potentially suitable agent for LT recipients who do not respond to PEG IFN‐α‐2b plus RBV after LT.     

Valproic acid,a histone deacetylase inhibitor,regulates cell proliferation in the adult zebrafish optic tectum

Background: Valproic acid (VPA) has been used to treat epilepsy and bipolar disorder. Several reports have demonstrated that VPA functions as a histone deacetylase (HDAC) inhibitor. While VPA is known to cause teratogenic changes in the embryonic zebrafish brain, its effects on neural stem cells (NSCs) in both the embryonic and adult zebrafish are not well understood. Results: In this study, we observed a proliferative effect of VPA on NSCs in the embryonic hindbrain. In contrast, VPA reduced cell proliferation in the adult zebrafish optic tectum. Treatment with HDAC inhibitors showed a similar inhibitory effect on cell proliferation in the adult zebrafish optic tectum, suggesting that VPA reduces cell proliferation through HDAC inhibition. Cell cycle progression was also suppressed in the optic tectum of the adult zebrafish brain because of HDAC inhibition. Recent studies have demonstrated that HDAC inhibits the Notch signaling pathway; hence, adult zebrafish were treated with a Notch inhibitor. This increased the number of proliferating cells in the adult zebrafish optic tectum with down‐regulated expression of her4, a target of Notch signaling. Conclusions: These results suggest that VPA inhibits HDAC activity and upregulates Notch signaling to reduce cell proliferation in the optic tectum of adult zebrafish. Developmental Dynamics 243:1401–1415, 2014. © 2014 Wiley Periodicals, Inc.     

Aldosterone-to-renin ratio and nocturnal blood pressure decline assessed by self-measurement of blood pressure at home: the Ohasama Study

Based on ambulatory blood pressure (BP) monitoring, the aldosterone-to-renin ratio (ARR) has been reported to be associated with a diminished nocturnal decline in BP, generally referred to as a “non-dipping” pattern. The objective of this cross-sectional study was to investigate the association between ARR and the non-dipping pattern based on home BP measurements. This study included 177 participants ≥55 years from the general population of Ohasama (mean age: 67.2 years; 74.6% women); no patient was receiving antihypertensive treatment. The median plasma renin activity (PRA), plasma aldosterone concentration (PAC) and ARR were 0.8?ng/mL/h, 8.1?ng/dL and 9.7?ng/dL per ng/mL/h, respectively. Each 1 SD increase in log-transformed (ln) ARR was significantly associated with the prevalence of the non-dipping pattern after adjustments for possible confounding factors including home morning systolic BP (odds ratio, 1.45; p?=?0.049). However, no significant associations of PRA or PAC with the non-dipping pattern were observed (p?≥?0.2). When participants were divided into four groups according to median levels of home morning and night-time systolic BPs, the group with a higher home morning systolic BP (≥128.4?mmHg) with a higher home night-time systolic BP (≥114.4?mmHg) had the greatest ARR levels (ANCOVA p?=?0.01). These results support the hypothesis that relative aldosterone excess may be related to a non-dipping pattern in a general population and suggest that a non-dipping pattern can be accurately observed by home BP measurements.     

Skeletal Muscle Loss Is Negatively Associated With Single‐Pool Kt/V and Dialysis Duration in Hemodialysis Patients

We evaluated the skeletal muscle loss in hemodialysis (HD) patients by bioelectrical impedance analysis (BIA) and handgrip strength test. Thirty‐four HD patients and 16 healthy subjects (control group) were measured for skeletal muscle mass normalized as the skeletal muscle mass index (SMI), calculated as skeletal muscle mass (kg)/height (m)² using a tetrapolar bioelectrical impedance plethysmograph. Handgrip strength test was also performed using a hand dynamometer in both groups. In HD patients, the associations of SMI and handgrip strength with age, sex, HD conditions, and HD parameters such as body mass index (BMI), single‐pool Kt/V (spKt/V), normalized protein catabolic rate (nPCR), creatinine generation rate (CGR) and serum albumin level (Alb) were investigated. SMI of HD patients (4.58 ± 0.95 kg/m²) was significantly lower than that of the control group (5.55 ± 0.80 kg/m², P < 0.01). The handgrip strength of HD patients (19.9 ± 7.74 kg) was also significantly lower than that of the control group (33.0 ± 8.94 kg, P < 0.01). In HD patients, HD duration was associated with both SMI and handgrip strength. Among HD parameters, spKt/V was negatively associated with both SMI and handgrip strength, BMI and Alb were positively associated with SMI, while nPCR and CGR were associated with neither SMI nor handgrip strength. HD duration independently contributed to skeletal muscle loss and the value of spKt/V may be affected by skeletal muscle loss in HD patients.     

Natural variation in a polyamine transporter determines paraquat tolerance in Arabidopsis

Polyamines (PAs) are ubiquitous, polycationic compounds that are essential for the growth and survival of all organisms. Although the PA-uptake system plays a key role in mammalian cancer and in plant survival, the underlying molecular mechanisms are not well understood. Here, we identified an Arabidopsis L-type amino acid transporter (LAT) family transporter, named RMV1 (resistant to methyl viologen 1), responsible for uptake of PA and its analog paraquat (PQ). The natural variation in PQ tolerance was determined in 22 Arabidopsis thaliana accessions based on the polymorphic variation of RMV1. An RMV1-GFP fusion protein localized to the plasma membrane in transformed cells. The Arabidopsis rmv1 mutant was highly resistant to PQ because of the reduction of PQ uptake activity. Uptake studies indicated that RMV1 mediates proton gradient-driven PQ transport. RMV1 overexpressing plants were hypersensitive to PA and PQ and showed elevated PA/PQ uptake activity, supporting the notion that PQ enters plant cells via a carrier system that inherently functions in PA transport. Furthermore, we demonstrated that polymorphic variation in RMV1 controls PA/PQ uptake activity. Our identification of a molecular entity for PA/PQ uptake and sensitivity provides an important clue for our understanding of the mechanism and biological significance of PA uptake.     

Specific mitochondrial DNA mutation in mice regulates diabetes and lymphoma development

It has been hypothesized that respiration defects caused by accumulation of pathogenic mitochondrial DNA (mtDNA) mutations and the resultant overproduction of reactive oxygen species (ROS) or lactates are responsible for aging and age-associated disorders, including diabetes and tumor development. However, there is no direct evidence to prove the involvement of mtDNA mutations in these processes, because it is difficult to exclude the possible involvement of nuclear DNA mutations. Our previous studies resolved this issue by using an mtDNA exchange technology and showed that a G13997A mtDNA mutation found in mouse tumor cells induces metastasis via ROS overproduction. Here, using transmitochondrial mice (mito-mice), which we had generated previously by introducing G13997A mtDNA from mouse tumor cells into mouse embryonic stem cells, we provide convincing evidence supporting part of the abovementioned hypothesis by showing that G13997A mtDNA regulates diabetes development, lymphoma formation, and metastasis--but not aging--in this model.